Ffrench-Constant C, Van de Water L, Dvorak H F, Hynes R O
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, 02139.
J Cell Biol. 1989 Aug;109(2):903-14. doi: 10.1083/jcb.109.2.903.
The adhesive extracellular matrix glycoprotein fibronectin (FN) is thought to play an important role in the cell migration associated with wound healing. Immunolocalization studies show abundant FN in healing wounds; however, these studies cannot define the cellular site(s) of FN synthesis, nor do they distinguish the different and potentially functionally distinct forms of FN that can arise from alternative splicing of the primary gene transcript. To examine these questions of FN synthesis and splicing during wound healing, we have performed in situ hybridization with segment-specific probes on healing wounds in adult rat skin. We find that the FN gene is expressed at increased levels after wounding both in the cells at the base of the wound and in subjacent muscle and dermis lateral to the wound. Interestingly, however, the pattern of splicing of FN mRNA was different in these areas. In adjacent dermis and muscle, the splicing pattern remains identical with that seen in normal adult rat skin, with two of the three spliced segments (EIIIA and EIIIB) excluded from FN mRNA. In contrast, these two segments are included in the FN mRNA present in the cells at the base of the wound. As a result, the mRNA in this region is spliced in a pattern identical with that found during early embryogenesis. The finding that the pattern of FN splicing during wound healing resembles an embryonic pattern suggests that alternative splicing may be used during wound healing as a mechanism to generate forms of FN that may be functionally more appropriate for the cell migration and proliferation associated with tissue repair.
黏附性细胞外基质糖蛋白纤连蛋白（FN）被认为在与伤口愈合相关的细胞迁移中起重要作用。免疫定位研究表明，愈合伤口中有大量FN；然而，这些研究无法确定FN合成的细胞位点，也无法区分由初级基因转录本的可变剪接产生的不同且可能功能不同的FN形式。为了研究伤口愈合过程中FN合成和剪接的这些问题，我们用片段特异性探针在成年大鼠皮肤的愈合伤口上进行了原位杂交。我们发现，受伤后，伤口底部的细胞以及伤口侧面相邻的肌肉和真皮中的FN基因表达水平都有所增加。然而，有趣的是，这些区域中FN mRNA的剪接模式不同。在相邻的真皮和肌肉中，剪接模式与正常成年大鼠皮肤中的相同，FN mRNA中排除了三个剪接片段中的两个（EIIIA和EIIIB）。相反，这两个片段包含在伤口底部细胞中的FN mRNA中。因此，该区域的mRNA剪接模式与早期胚胎发育过程中发现的模式相同。伤口愈合过程中FN剪接模式类似于胚胎模式这一发现表明，可变剪接可能在伤口愈合过程中被用作一种机制，以产生在功能上可能更适合与组织修复相关的细胞迁移和增殖的FN形式。
